ERTH 4303 Lecture Notes - Lecture 5: Autotroph, Primary Production, Mechanical Advantage
5 Mar 2018
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Document Summary
Energy: a property of matter that can be transferred to other matter to perform work on it or heat it up. Exergy: amount of work that can be done in an ideal process; is destroyed by an increase in entropy. Power: 1w = 1j/s, the rate of flow of energy. Incandescent light bulb dissipates 95% electrical energy as heat. Energy intensity: gj/t, the amount of energy required to produce something. Energy intensity of energy: j/j, the amount of energy expended to produce a useable form of energy; for instance, it may take more energy to produce corn ethanol than it contains. Energy density: j/m3, the energy content per unit volume. Specific energy: j/kg, the energy content per unit mass. Energy concentration: j/m2, the spatial density of resources like fossil fuels or trees. Power density: w/m2, the rate of energy flow per unit of surface area. Specific power: w/g, the intensity of metabolism or power generation per unit mass.
